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"There's an argument about whether viruses are 'alive', since they depend on others' cells to make their proteins. Prions are even less considered 'alive' ..."

• teachingassist 5y ago
  > does anyone ever suggest a prion LUCA[1] Yes, it totally makes sense to talk about a common ancestor! There's one known prion-disease-causing protein in humans, the "major prion protein". You can see the gene containing the code for this protein in human DNA, and any mammal DNA has a similar gene that is still very closely related. This suggests that the protein has some important function(s) in mammals, and has a common ancestor before these species existed. Genes that have a shared history but are less closely related (and don't appear to cause disease) can be found for example also in zebrafish ('Shadoo' gene) and in humans ('Doppel' gene). https://pubmed.ncbi.nlm.nih.gov/15449459/ https://pubmed.ncbi.nlm.nih.gov/15449459/